There are a handful of horns that really benefit from damping and/or destressing, and the plastic piezo sure couldn't hurt from added mass. So I can certainly see this as an attractive thing that can be done, in the spirit of "tender loving care."As for the drivers themselves, I've rarely seriously considered modifying them - particularly the diaphragms - because it's too hard to maintain consistency by hand. I suppose a precise mass could be glued between the cone and spider to lower resonance of a woofer or something, but with so many choices available and companies willing to build to spec, this doesn't really make sense to me. Basically, I tend to take the attitude that I'll choose a different part if I don't like it's characteristics.
That's not to say that I've never applied something to the diaphragm of a speaker. I've repaired cones that were ripped, and I've even colored some that were discolored. But that's more a repair issue, and something done as an option in lieu of reconing. I don't do this as a planned modification or a "tweak." Basically, I'm just not big on the whole tweaking biz. I build 'em according to the numbers, use good parts and enjoy the sound.
But there's always room for improvement. There's certainly a lot of things that can be done and it stands to reason that the greatest improvements can be made to the least expensive speakers. So if you're doing something that's working and you like it, then I'd say it's time well spent.
Thanks for your input. I think maybe I'll surround a KSN-1038 with clay and compare it with a stock part in a pair of one π or two π speakers. You've got me curious now!